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Why Does My Chimney Stink?

Whether it starts suddenly or builds over time, an unidentified chimney odor can make your home uncomfortable and stinky. Instead of turning to air fresheners or scented candles, it is important to identify and repair the root cause of a stinky chimney. This helps to keep chimney odors from coming back, and it also improves the air quality in your home. At Clean Sweeps of Michigan, we want to help you learn some things that can cause your chimney to stink and how we can help with it.

What causes stinky chimneys?

masonry chimney on side of homeUnfortunately, there is not one hard and fast rule for what causes stinky chimneys. Different odors have different causes. Often, a chimney inspection is all you need to uncover the root cause of an odor. The following are four of the most common causes of stinky chimneys.


Odors associated with animal entry usually start suddenly. They are usually sharp or rotting odors and are often accompanied by the sounds of scurrying or scratching in the chimney. Birds, raccoons, and squirrels are just some of the animals that can – whether on purpose or an accident – become trapped in your chimney. Animal feces, food, drying nesting materials, or even dead animals can cause serious odors to overwhelm your entire home. In addition, they can carry bacteria, pests, and other microorganisms. Because of this, it is important to have animals professionally removed as soon as possible.


Creosote is a dark, sticky byproduct of fuel-burning fires that accumulates in the flue. While small amounts of creosote buildup occur with regular fireplace use, not having the chimney regularly swept or burning green or wet wood can cause extra creosote accumulation. Smoky or dirty smells are the result of hot or humid weather mixing with creosote buildup inside your chimney.

While the outside of the chimney is designed to withstand exposure to water, the inside is not. The presence of water in the chimney is often the result of a chimney leak. Leaky chimneys can cause dank, damp odors, as water has trouble evaporating in the cool, dark chimney.


In addition, water in the firebox or chimney can lead to mold or mildew growth, which can significantly negatively impact the air quality in the home. People with respiratory conditions such as asthma are at risk of health complications such as breathing issues when mold is present.


Drafting issues can cause smoky fireplace odors too. However, smells associated with drafting issues are most common on windy days – and when the fireplace is in use. Drafting issues are commonly caused by a flue that is the wrong size. If a new insert has been installed or if the fuel source of the fireplace has been changed, the flue may need to be relined to ensure proper draft.

Don’t let a stinky chimney ruin the air quality in your home. Instead, you should invest in fireplace experts at Clean Sweeps of Michigan today. Our chimney experts can provide you with more information on chimney odors or your next chimney inspection.

What the Cold Can Do to Your Chimney

What the Cold Can Do To Your Chimney - Ann Arbor MI - Clean Sweeps of MichiganOne of the main purposes of having a fireplace, stove, or other fuel burning appliance is to help heat your home during the cold months of winter. While fireplaces are designed to keep us warm during the cold, the cold can often have a negative impact on chimneys.

The ice, snow, and freezing temperatures we experience during winter can damage your chimney or make existing damage worse. The following are just a few of the ways that the cold can negatively affect your chimney.

The stack effect

The stack effect can cause smoke to backdraft into your home. When the temperature outside is significantly colder than the air temperature inside, as is often the cause during winter, the cooler outside air will rush down the chimney shaft to replace the rising warm air.

These backdrafts can be prevented by keeping the damper closed when the fireplace is not in use. In addition, warming the flue may help prevent smoke from blowing back into the room immediately after a fire is lit. To warm the flue, light a small amount of kindling and hold it under the open damper for several minutes before lighting the rest of the fire. Doing this gradually warms the air in the flue which prevents a rush of cold air from flooding down as the fire is lit.

Water damage

The primary cause of chimney deterioration during the winter months is water damage. Bricks that are cracked or chipped can absorb water from snow and rain, which then freezes as the temperatures drop. The water in the brick expands, creating bigger and bigger cracks or holes. As the water melts, more and more water can enter the brick. This freeze thaw process can cause bricks to crumble and fall away from the chimney.

Likewise, melting snow and ice may cause a leak in the chimney structure. While identifying the cause of a leak may be difficult, it should be done as quickly as possible to prevent water damage to the chimney, flue, or other fireplace structures.

Animal entry

When the temperature outside drops, people tend to spend more time inside to escape the elements. Unfortunately, animals are the same way. Animals such as birds, raccoons, and squirrels often view chimneys are warm, protected placing to spend the winter. You might not even realize they are in there until there is a foul odor.

If you have animals in your chimney, the first step is to have them safely removed by a wildlife professional. Homeowners should not attempt to smoke out the animals by starting a fire or remove animals themselves, as many wild animals may carry diseases. This can also cause smoke and carbon monoxide build up in your home if the smoke from the fire has nowhere to escape.

After the animals have been removed, it is important to have your chimney inspected by a certified chimney sweep. Chimney sweeps can make masonry repairs to prevent animals from coming back as well as remove any blockages left behind in the chimney, which can damage the flue lining or cause smoke and gas to back up into your home.

If you think this winter’s cold weather has damaged your chimney, contact Clean Sweeps of Michigan today. Our certified chimney sweeps can inspect and clean your chimney and give you the peace of mind to continue enjoying your fireplace.

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